"Loudness war" or "loudness race" is the popular name given to the trend of increasing audio levels on CDs and in digital audio files since the early 1990s, which many critics believe reduces sound quality and listener enjoyment. Increasing loudness was first reported[by whom?] as early as the 1940s with respect to mastering practices for 7" singles. The maximum peak level of analog recordings such as these is limited by varying specifications of electronic equipment along the chain from source to listener, including vinyl record and cassette players.

With the advent of the Compact Disc (CD), music is encoded to a digital format with a clearly defined maximum peak amplitude. Once the maximum amplitude of a CD is reached, loudness can be increased still further through signal processing techniques such as dynamic range compression and equalization. Engineers can apply an increasingly high ratio of compression to a recording until it more frequently peaks at the maximum amplitude. In extreme cases, efforts to increase loudness can result in clipping and other audible distortion. Modern recordings that use extreme dynamic range compression and other measures to increase loudness therefore can sacrifice sound quality to loudness. The competitive escalation of loudness has led music fans and members of the musical press to refer to the affected albums as "victims of the loudness war."

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The practice of focusing on loudness in mastering can be traced back to the introduction of the compact disc itself, but also existed to some extent when vinyl was the primary released recording medium and when 7" singles were played on jukebox machines in clubs and bars.

Jukeboxes became popular in the 1940s and were often set to a predetermined level by the owner, yet any record that was mastered louder than the others would stand out. Similarly, starting in the 1950s, producers would request louder 7" singles so that songs would stand out when auditioned by program directors for top 40 radio stations.[1] In particular, many Motown records pushed the limits of how loud records could be made; according to one of their engineers, they were "notorious for cutting some of the hottest 45s in the industry."[2] In the 1960s and 1970s, various artists hit compilation albums became popular and, when artists and producers found their song was quieter than others on the compilation, they would insist that their song be remastered to be competitive.

However, because of the limitations of the vinyl format, loudness and compression on a released recording were restricted to make the physical medium playable—restrictions that do not exist on digital media such as CDs—and as a result, increasing loudness levels never reached the significance that they have in the CD era.[3] In addition, modern computer-based digital audio effects processing allows mastering engineers to have greater control over the loudness of a song; for example a "brick wall" limiter can look ahead at an upcoming signal to limit its level.[4]

The stages of the CDs loudness increase are often split over the three decades of the medium's existence. Since CDs were not the primary medium for popular music until the late 1980s, there was little motivation for competitive loudness practices then. CD players were also very expensive and thus commonly exclusive to high-end systems that would show the shortcomings of higher recording levels.

As a result, the common practice of mastering music involved matching the highest peak of a recording at, or close to, digital full scale, and referring to digital levels along the lines of more familiar analog VU meters. When using VU meters, a certain point (usually −14 dB below the disc's maximum amplitude) was used in the same way as the saturation point (signified as 0 dB) of analog recording, with several dB of the CD's recording level reserved for amplitude exceeding the saturation point (often referred to as the "red zone", signified by a red bar in the meter display), because digital media cannot exceed 0 decibels relative to full scale (dBFS). The average level of the average rock song during most of the decade was around −18 dBFS.[citation needed]

In the early 1990s, CDs with louder music levels began to surface, and CD levels became more and more likely to bump up to the digital limit,[note 1] resulting in recordings where the peaks on an average rock or beat-heavy pop CD hovered near 0 dB,[note 2] but only occasionally reached it.[6][not in citation given]

The concept of making music releases "hotter" began to appeal to people within the industry, in part because of how noticeably louder some releases had become and also in part because the industry believed that customers preferred louder sounding CDs, even though that may not have been true.[7] Engineers, musicians, and labels each developed their own ideas of how CDs could be made louder.[citation needed] In 1994, the digital brickwall limiter with look-ahead (to pull down peak levels before they happened) was first mass-produced. While the increase in CD loudness was gradual throughout the 1990s, some opted to push the format to the limit, such as on Oasis's widely popular album (What's the Story) Morning Glory?, which averaged −8 dBFS on many of its tracks—a rare occurrence, especially in the year it was released (1995). In 1997, Iggy Pop assisted in the remix and remaster of the 1973 album Raw Power by his former band The Stooges, driving the level to −4 dBFS in places.[6]

In late 2008, mastering engineer Bob Ludwig offered three versions of the Guns N' Roses album Chinese Democracy for approval to co-producers Axl Rose and Caram Costanzo. They selected the one with the least compression. Ludwig wrote, "I was floored when I heard they decided to go with my full dynamics version and the loudness-for-loudness-sake versions be damned."[15] Ludwig said the "fan and press backlash against the recent heavily compressed recordings finally set the context for someone to take a stand and return to putting music and dynamics above sheer level."[15]

In March 2010, mastering engineer Ian Shepherd organised the first Dynamic Range Day,[16] a day of online activity intended to raise awareness of the issue and promote the idea that "Dynamic music sounds better". The day was a success and its follow-ups in the following years have built on this, gaining industry support from companies like SSL, Bowers & Wilkins, TC Electronic and Shure[17] as well as engineers like Bob Ludwig, Guy Massey and Steve Lillywhite.[18] Shepherd cites research showing there is no connection between sales and "loudness", and that people prefer more dynamic music.[19][20] He also argues that file-based loudness normalization will eventually render the war irrelevant.[21]

One of the biggest albums of 2013 was Daft Punk's Random Access Memories, with many reviews commenting on the album's great sound.[22][23] Mixing engineer Mick Guzauski deliberately chose to use less compression on the project, commenting "We never tried to make it loud and I think it sounds better for it."[24] The album's opening track, Give Life Back To Music, may as well be understood as hinting at this issue in the great part of modern music productions. In January 2014 the album won five Grammy Awards, including Best Engineered Album (Non-Classical).[25]

In October 2013, Bob Katz announced on his website that "The last battle of the loudness war has been won", claiming that Apple's mandatory use of Sound Check for iTunes Radio meant that "The way to turn the loudness race around right now, is for every producer and mastering engineer to ask their clients if they have heard iTunes Radio. When they respond in the affirmative, the engineer/producer tells them they need to turn down the level of their song(s) to the standard level or iTunes Radio will do it for them. He or she should also explain that overcompressed material sounds wimpy and small in comparison to more open material on iTunes Radio." He believes this will eventually result in producers and engineers making more dynamic masters to take account of this factor.[26] His point of view has been widely reported and discussed.[27][28]

Analysis suggests that the loudness trend may have peaked around 2005 and subsequently reduced, with a pronounced increase in overall and minimum album DR (crest factor) for albums since 2005.[29][30]

With music sales moving towards file-based playback, digital downloads and away from CDs, there is a possibility that the loudness war will be blunted by normalization technology such as ReplayGain and Apple's Sound Check.[31] Most cloud-based music services perform loudness normalization by default and may reduce the market pressure to hypercompress material.[32]

Replay volume normalization also helps when listening to playlists or shuffle play where otherwise variations in perceived loudness of recordings results in uncomfortable loudness shifts.[33]

In August 2011, the EBU published EBU Recommendation R 128,[34] which specifies a new way of metering and normalizing audio, based on ITU-R BS.1770. It is accompanied by the EBU Loudness Metering specification EBU Tech 3341,[35] which includes the so-called 'EBU Mode' to make meters interoperable. Also, a Loudness Range descriptor is defined, in EBU Tech 3342,[36] which helps audio mixers understand what loudness range their material consists of.[37]

Broadcasting is also a participant in the loudness war. Competition for listeners between radio stations and competition for clients between recording studios[dubious– discuss] has also caused a loudness "arms race".[38] Loudness jumps between broadcast channels and between programmes within the same channel, and between programs and intervening adverts are a frequent source of audience complaints.[citation needed] The European Broadcasting Union is addressing this issue in the EBU PLOUD Group, which includes over 230 audio professionals, many from broadcasters and equipment manufacturers.

This practice (excessive compression, dynamic range reduction, loudness level enhancement, etc.) has been condemned by several recording industry professionals including Alan Parsons, Geoff Emerick[39] (noted for his work with The Beatles from Revolver to Abbey Road), and mastering engineers Doug Sax,[2]Steve Hoffman, and many others, including music audiophiles, hi-fi enthusiasts, and fans. Musician Bob Dylan has also condemned the practice, saying: "You listen to these modern records, they're atrocious, they have sound all over them. There's no definition of nothing, no vocal, no nothing, just like—static." The compact disc editions of Dylan's more recent albums Modern Times and Together Through Life are examples of heavy dynamic range compression, although Dylan himself might not have been responsible for it.[40]

When music is broadcast over radio, the station applies its own signal processing, further reducing the dynamic range of the material to closely match levels of absolute amplitude, regardless of the original recording's loudness.[41]

Opponents have called for immediate changes in the music industry regarding the level of loudness. In August 2006, the vice-president of A&R for One Haven Music, a Sony Music company, in an open letter decrying the loudness war, claimed that mastering engineers are being forced against their will or are preemptively making releases louder to get the attention of industry heads.[3] Some bands are being petitioned by the public to re-release their music with less distortion.[39]

The nonprofit organization Turn Me Up![42] was created by Charles Dye, John Ralston and Allen Wagner to certify albums that contain a suitable level of dynamic range[43] and encourage the sale of quieter records by placing a "Turn Me Up!" sticker on albums that have a larger dynamic range.[44] The group has not yet arrived at an objective method for determining what will be certified.[45]

Hearing experts, such as a hearing researcher at House Ear Institute in Los Angeles, are also concerned that the loudness of new albums could possibly harm listeners' hearing, particularly that of children.[44]

The book Perfecting Sound Forever: An Aural History of Recorded Music (Faber, 2009), by Greg Milner presents the Loudness war in radio and music production as a central theme. The book Mastering Audio: The Art and the Science (2nd Edition, Focal Press, 2007), by Bob Katz, includes a chapter about the origins of the loudness war and another suggesting methods of combatting the war, based on Katz's presentation at the 107th Audio Engineering Convention (1999) and his Audio Engineering Society Journal publication (2000).[50]

In 2007, Suhas Sreedhar published an article about the loudness war in the engineering magazine IEEE Spectrum.[33] Sreedhar said that the greater possible dynamic range of CDs was being set aside in favor of maximizing loudness using digital technology. Sreedhar said that the overcompressed modern music was fatiguing, that it did not allow the music to "breathe".[33]

In September 2011, Emmanuel Deruty wrote in Sound on Sound, a recording industry magazine, that the loudness war has not led to a decrease in dynamic variability in modern music, possibly because the original digitally-recorded source material of modern recordings is more dynamic than analogue material.[30] Deruty and Damien Tardieu criticized Sreedhar's methods in an AES paper, saying that Sreedhar had confused crest factor (peak minus RMS) with dynamics in the musical sense (pianissimo to fortissimo).[51] Deruty and Tardieu analyzed the "loudness range" (LRA) over a 45-year span of recordings, and observed that the crest factor of recorded music diminished significantly between 1985 and 2010, but the LRA remained relatively constant.[30]

This analysis been challenged on the basis that the LRA was designed for assessing loudness variation within a track while the EBU R128 Peak to Loudness Ratio (PLR) is a measure of the peak level of a track relative to a reference loudness level. Ian Shepherd and Bob Katz wrote that PLR is a more helpful metric in assessing overall perceived dynamic range which shows a trend toward reduced dynamic range throughout the 1990s.[52][53]

Debate continues regarding which measurement methods are most appropriate to evaluating the loudness war.[54][55][56]

^Viney, Dave (December 2008). "The Obsession With Compression". p. 54. Retrieved 24 July 2011. there is no evidence of any significant correlation between loudness (& implied compression) and commercial success